Abstract: A method may include determining a power level of a signal and a temperature level of a transmitter originating the signal. At least one of the power and temperature levels may be compared to a lookup table containing predistortion coefficients. The method is capable of predistorting a signal based on the comparison. An apparatus is disclosed in relation to the method.

Abstract: A method is provided to accurately predict the probability of successfully recovering frames of (coded) information received over a wireless link, without having to decode the frame. This method, which consists of three steps, requires only limited information about the received signals and the forward error correction code and retransmission scheme being used. First, the signal to noise ratio (SNR) of each of the received signals is measured, where the average SNR is determined for multiple segments that together constitute the frame. Next, an algorithm is employed that takes these SNR values as inputs and determines the so-called effective SNR. The algorithm translates the measured SNR values using an appropriate convex metric, and subsequently combines the resulting values, thereby factoring in the effects of fading, multi-path, and other signal degradations.

Abstract: A predistortion system and method uses an inner predistortion function to adjust a signal being input into a distortion generating circuit and at least one outer predistortion function to adjust the signal being input into the inner predistortion function. Thus, the inner predistortion function can reduce the distortion from the distortion generating circuitry, and any remaining distortion can be reduced by the outer predistortion function.

Abstract: Disclosed is an apparatus and method for modeling and estimating the characteristics of a power amplifier with memory. A predistortion module generates a predistorted signal in response to coefficients of a complex polynomial representative of the amplifier and to an input signal. A power amplifier receives time-spaced samples of the predistorted signal and generates an output signal. A polynomial module updates the coefficients of the complex polynomial in response to a current sample of the output signal and to the time-spaced samples of the predistorted signal. In particular, the complex polynomial is implemented with both even and odd terms.

Abstract: A method may include determining a power level of a signal and a temperature level of a transmitter originating the signal. At least one of the power and temperature levels may be compared to a lookup table containing predistortion coefficients. The method is capable of predistorting a signal based on the comparison. An apparatus is disclosed in relation to the method.

Abstract: A signal is predistorted by producing a first set of sample values using a first predistortion technique, producing a second set of sample values using a second predistortion technique different than the first predistortion technique, and combining the first and second sets of sample values to produce a predistorted signal. At least one of the first and second predistortion techniques produce the corresponding set of sample values based at least in part on a plurality of past time spaced input samples relative to a current time spaced input sample.

Abstract: A predistortion system compensates or equalizes the phase and/or amplitude response over frequency of at least a portion of a signal path prior to the distortion generating circuitry, such as an amplifier, and/or of at least a portion of a feedback path after the distortion generating circuitry. For example, in a power amplification system using predistortion, an equalizer on the signal path adjusts the phase and amplitude of a predistorted signal across frequency to compensate for the amplitude and phase response of circuitry on the signal path, such as the amplitude and phase response of analog filters in the up-conversion process. After amplification, an equalizer on a feedback path adjusts the phase and amplitude across frequency of the signal representing the output of the amplifier to compensate for the amplitude and phase response of circuitry, such as analog filters in the down-conversion process, on the feedback path.

Abstract: A tracking circuit fine tunes the sampling time to a resolution of ⅛ Tc, where Tc is a chip duration after the searcher circuit finds the timing to within 0.5 Tc. Depending on the prior art tracking circuit that is being used, the input signals are early and late sampled PN despread pilot symbols or early, late and ontime sampled PN despread pilot symbols. Early and late samples are plus or minus one tick or Tt (one tick is ⅛ Tc) away from the ontime samples. The basic principle is that if early and late samples have about the same energy, then the timing is correct. If not, then the sampling time is changed to obtain a balance. In this invention, improved performance of the prior art tracking circuit is obtained by using pilot estimation results, not ontime pilot symbols. In one embodiment, pilot estimation results are low pass filtered signals of ontime symbols which are normally generated upstream of the tracking circuit.

Abstract: A signal is predistorted by producing a first set of sample values using a first predistortion technique, producing a second set of sample values using a second predistortion technique different than the first predistortion technique, and combining the first and second sets of sample values to produce a predistorted signal. At least one of the first and second predistortion techniques produce the corresponding set of sample values based at least in part on a plurality of past time spaced input samples relative to a current time spaced input sample.

Abstract: A time-efficient real-time correlator is provided for use in a receiver of a wireless communications system. The correlator correlates a signal received by the receiver with a pseudo-random number (PN) code in order to determine the time delay of the received signal. The correlator requires no memory for storing samples of the received signal. A shift register having only W storage elements is utilized for storing the samples of the PN code sequence, where W is a positive integer corresponding to the length of the correlation window. W+1 correlation results storage elements are utilized to store correlation result values. When the correlator receives a current sample of the incoming signal, the current sample r(j) is multiplied by each of the samples of the PN code sequence to obtain products. The correlation result values stored in the correlation results storage elements are added to the products and the resulting sum is stored in the correlation results storage elements.

Abstract: A method for softlimiting or clipping a signal. The method includes the step of searching for at least the highest peak above a threshold within a first window created from a set of samples of the signal. Thereafter, a threshold-correcting signal is added to the highest peak found.

Abstract: A predistortion system uses a predistortion function which is a combination of functions which are dependent on one of a plurality of time spaced samples of the input signal and independent of the other samples. Using such a structure for the predistortion function enables an easier and low cost implementation. For example, a plurality of time spaced samples are used by predistortion circuitry to produce the predistorted signal. The predistortion circuitry includes first function ciruitry which produces a current sample output value depending on a current input sample and independent of a delayed input sample. A second function produces a delayed sample output value depending on the delayed input sample and independent of the current input sample. Each of any additional functions produces an additional delayed sample output value depending on an additional delayed input sample and independent of any other input samples. The sample output values are combined to produce the predistorted sample.

Abstract: A method is disclosed for deriving an optimum decision criteria to detect forward link power control bits by a base station from a reverse link signal. In managing the forward link received power, a mobile station commands the base station to incrementally alter the forward link transmit power, by sending periodic power control bits to the base station on a reverse link signal. The transmitted power control bits may be distorted by channel imperfections and multipath effects. The method disclosed derives an optimum decision variable for performing power control bit estimation at the base station. In a preferred embodiment, the optimum decision variable is computed by considering the in-phase and quadrature components of a single power control group received on the reverse pilot channel.

Abstract: A predistortion system compensates or equalizes the phase and/or amplitude response over frequency of at least a portion of a signal path prior to the distortion generating circuitry, such as an amplifier, and/or of at least a portion of a feedback path after the distortion generating circuitry. For example, in a power amplification system using predistortion, an equalizer on the signal path adjusts the phase and amplitude of a predistorted signal across frequency to compensate for the amplitude and phase response of circuitry on the signal path, such as the amplitude and phase response of analog filters in the up-conversion process. After amplification, an equalizer on a feedback path adjusts the phase and amplitude across frequency of the signal representing the output of the amplifier to compensate for the amplitude and phase response of circuitry, such as analog filters in the down-conversion process, on the feedback path.

Abstract: A multiple stage and/or nested predistortion system and method uses an inner predistortion function to adjust a signal being input into a distortion generating circuit and at least one outer predistortion function to adjust the signal being input into the inner predistortion function. Thus, the inner predistortion function can reduce the distortion from the distortion generating circuitry, and any remaining distortion can be reduced by the outer predistortion function. For example, in an adaptive predistortion system where the distortion generating circuit is an amplifier, an inner predistortion loop comprises an inner predistortion function which distorts the signal on the main signal path prior to the amplifier. The inner predistortion function can be produced using an output of the inner predistortion function and an output of the amplifier. An outer predistortion loop comprises an outer predistortion function which distorts the input signal prior to the inner predistortion function.

Abstract: Disclosed is an apparatus and method for modeling and estimating the characteristics of a power amplifier. A predistortion module generates a predistorted signal in response to a predistortion function and an input signal. A power amplifier receives the predistorted signal and generates an output signal. A polynomial module generates coefficients of a complex polynomial of order p (p is an integer greater than one) in response to the predistorted signal and the output signal. In particular, the complex polynomial is inplemented with both even and odd terms, thereby improving the ability to accurately model the power amplifier.

Abstract: Disclosed is an apparatus and method for modeling and estimating the characteristics of a power amplifier. A predistortion module generates a predistorted signal in response to a predistortion function and an input signal. A power amplifier receives the predistorted signal and generates an output signal. A polynomial module generates coefficients of a complex polynomial of order p (p is an integer greater than one) in response to the predistorted signal and the output signal. In particular, the complex polynomial is implemented with both even and odd terms, thereby improving the ability to accurately model the power amplifier.

Abstract: Disclosed is an apparatus and method for iteratively calculating the predistortion function from a power amplifier when the inverse to the power amplifier characterization does not exist analytically. A predistortion module generates a predistorted signal in response to an input signal and a predistortion function received from a predistortion function calculating module. The predistortion function calculating module generates the predistortion function in response to given amplifier characteristics. In particular, the predistortion function calculating module uses a magnitude of the input signal at a given time to estimate the predistorted signal at that given time in order to calculate the predistortion function. Optionally, subsequent iterations based on the magnitude of the estimate occur until a desired accuracy of the predistorted signal approximation and of the predistortion function is achieved.

Abstract: Disclosed is an apparatus and method for iteratively calculating the predistortion function from a power amplifier when the inverse to the power amplifier characterization does not exist analytically. A predistortion module generates a predistorted signal in response to an input signal and a predistortion function received from a predistortion function calculating module. The predistortion function calculating module generates the predistortion function in response to given amplifier characteristics. In particular, the predistortion function calculating module uses a magnitude of the input signal at a given time to estimate the predistorted signal at that given time in order to calculate the predistortion function. Optionally, subsequent iterations based on the magnitude of the estimate occur until a desired accuracy of the predistorted signal approximation and of the predistortion function is achieved.

Abstract: Disclosed is an apparatus and method for modeling and estimating the characteristics of a power amplifier with memory. A predistortion module generates a predistorted signal in response to coefficients of a complex polynomial representative of the amplifier and to an input signal. A power amplifier receives time-spaced samples of the predistorted signal and generates an output signal. A polynomial module updates the coefficients of the complex polynomial in response to a current sample of the output signal and to the time-spaced samples of the predistorted signal. In particular, the complex polynomial is implemented with both even and odd terms.